Projection system



Nov. 29, 1966 R. E. PLUMP PROJECTION SYSTEM Filed Jan. 2, 1964 FIG].

SCREEN ELECTRON eu/v FIG.2.

v -v s I n u. u I. 1

INVENTORI RALPH E. PLUMP,

HIS ATTORNEY.

United States Patent M 3,283,927 PRQJTJCTION SYSTEM Ralph E. Plump,Taftsville, Vt., assignor to General Electric Company, a corporation ofNew York Filed Jan. 2, 1964, Ser. No. 335,151 6 Claims. (Cl. 178--7.5)

This invention relates to projection systems of the electronic type.More particularly, it relates to such projection systems having acontainer with a conducting interior and a deformable medium in thecontainer that decreases in resistivity with decreases in thickness inthe presence of an electrical charge on the surface of the medium, themedium being the polymeric reaction product of benzyl chloride andaromatic compounds.

There is described in US. Patent No. 2,943,147, June 28, 1960, assignedto the same .assignee as the present invention, a projection system ofthe above type employing a deformable medium having a high resistivitywhich is responsive to a velocity modulated electron beam. Generallyspeaking, this projection system, which is illustrated in FIG. 1 of thedrawing, comprises an evacuated glass envelope 10 containing an electrongun 11 for producing an electron beam 13 deflecting the beam in arectangular raster over the surface of a light transmitting deformablemedium 15 which is within a portion 17 of the transparent container. Anenlarged view of this portion of the assembly is shown in FIG. 2. Thebeam 13 is preferably velocity-modulated by a television signal appliedto the deflection means (not shown) in the electron gun 11. Deformablemedium 15 has a central portion 19 of decreased thickness which iscoincident with the raster area of beam 13 produced by electrons frombeam 13 which are attracted to a conducting coating 21 on the innersurface of the container portion 17. These same electrons also producedeformations in the surface of the deformable medium 15 and theamplitudes of these deformations are a function of the number ofelectrons deposited by the beam 13 at the various points on the surfaceof medium 15. Thus, the amplitudes of these deformations are a functionof the modulated electron beam 13.

The deformations on the surface of medium 15 are utilized to diffractlight from a source 23 in an optical system which includes a lens 24which projects an image of light source 23 on the surface of medium 15through a bar and slit system 25. Another lens 29 images the slits ofsystem 25 on the bars of another bar and slit system 31 if there are nodeformations on the surface of deformable medium 15. However, anydeformations on such surface diffract the transient light so that itpasses through the slits in the system 31 with an intensity thatcorresponds to the amplitudes of the deformations and hence theamplitudes of the applied modulating signal such as a television signal.The light passing through system 29 is imaged by a projection lens 33 onscreen 355 by means of mirror 37.

If a conventional deformable medium is utilized at 15 in the illustratedsystem, the average charge density produces a force on the medium 15that overcomes the surface tension from the excess medium outside theraster area and decreases the portion 19 of medium 15 to zero thickness.Under such conditions, no deformations can be formed and the systembecomes inoperative until the medium is replaced. The above patentteaches that if the medium has the property of decreasing in resistivitywith decreasing thickness, portion 19 does not decrease to Zerothickness under the pressure of the charges but maintains a thicknesswhich is a function of the magnitude of charge density on the surface ofthe medium 15. With decrease in resistivity, the time constant isdecreased for the passage of leakage current from the surface ofdeformable medium 15 to the conducting coating beneath it. This3,288,927 Patented Nov. 29, 1966 results in an increase in leakagecurrent, decreasing the charge density on the surface of the medium 15and somewhat relieving the pressure. Eventually, an equilibriumcondition is reached in which the pressure from the charges on thesurface of the medium equals the pressure from the surface tension onthe excess medium surrounding the raster at which the thickness at thisequilibrium condition is maintained. The charge density on the surfaceof the medium never decreases to zero because of such leakage because itis continually being replaced by electrons from beam 13.

The deformable composition described in the aforesaid patent, US.2,943,147, as suitable for the medium are required to be transparent, becapable of withstanding electron bombardment without significantdecomposition, have a viscosity at the operating temperature (betweenabout 25 C. and 150 C.) of approximately to 50,000 centistokes, and thedeformable composition must not decompose the conducting coating. Themedium must also have a volume resistivity that varies within the rangeof approximately 10 to 10 ohms-crn, with the average resistivity at thestable thickness being approximately 10 ohms-cm.

Among the deformable media or fluids described in this patent are, forinstance, beeswax, methyl silicone fluids, methyl silicone fluidscontaining up to 5% of phenyl silicones, methylphenyl siliconescontaining an average of two methyl and phenyl groups per silicon atomin which the mole ratio of methyl groups to silicon atoms is greaterthan 0 and less than 2, etc. However, it has been found that thesedeformable fluids are not as stable as one would desire because underthe influence of an electron beam, the deformable medium or deformablefluids tends to increase in viscosity and with continued use of theprojection system described above, the viscosity increases to a pointwhere gel particles begin to form and ultimately the deformable mediumgels. This means that the apparatus can no longer be used with thatparticular deformable medium.

From the above, it will be apparent that there is a definite need formaterials which can be used as medium 15 which are characterized by adesirably low rate of thickening under the radiation effects ofelectrons from beam 13. At the same time, such materials should becharacterized by good writing behavior under the action of electrons.They should have a good general working viscosity, that is, they shouldnot be too thin. They should have a suitably low vapor pressure and theyshould be economical.

It is therefore a principal object of the invention to provide materialswhich are possessed of such desirable qualities.

It has been unexpectedly found that the polymeric Friedel-Craftsreaction products of chloroalkylated aromatic materials, such as benzylchloride, with other aromatic hydrocarbons admirably fit the abovecharacteristics and provide a deformable medium which is possessed oflong working life. Specifically, such materials which have a viscosityof at least 100 centistokes (cs.) at 25 C. and have other desirablequalities have been found to be useful. Materials with a lower viscosityhave an undesirably high vapor pressure.

Benzyl chloride is the preferred chloroalkylated material used herein.It will, of course, be appreciated that other halo-substituted benzylmaterials of the above de scription can be used such as the iodoandbromo-substituted materials. However, the chloro-substituted materialsare preferred from the point of view of cost and ready availability aswell as from the point of view of easier processing.

Among the aromatic hydrocarbons which can be used are benzene, toluene,benzyl toluene and diphenyl methane. It is important that no alkylgroups higher than methyl groups be included as ring substituents in thearomatic material in order that gasification be held to a inimum underelectron iradiation. Blends of such materials can also be used. Aluminumchloride is preferred as the catalyst material but other materials, suchas zinc chloride, ferric chloride, mercury zinc amalgam, mercury sodiumamalgam as well as various silicate materials, can be used.

Generally speaking, in forming the present materials preferably fromabout 0.8 to 3 moles of chloromethylated aromatic material, such asbenzyl chloride, are used for each mole or aromatic hydrocarbon. Broadlyspeaking, from about 0.1 to about moles of chloromethylated material isused for each mole of aromatic hydrocarbon.

Example 1 Dry toluene in the amount of 460 grams (5 moles) was stirredand slowly heated with grams of a 1:1 by weight powdered mixture of zincchloride and magnesium Ce kate while benzyl chloride in the amount of949 grams (7.5 moles) was added dropwise for about four hours, thetemperature meanwhile being raised from about 45 C. to 89 C. Celk'ate isa synthetic magnesium silicate material made by the lohns-ManvilleCorporation. The batch was then stirred for about 16 hours at 9093 C.after which the reaction was complete as judged by the absence of HCl.Next, a filtering aid was added, and 300 cc. of toluene also, for itsthinning effect, after which the batch was filtered and shaken with 250cc. of about 30% caustic soda. The organic product layer was dried,filtered and distilled. After removing the excess and unreacted toluene,intermediate fractions were distilled off. The following table shows theitractions obtained, their principal composition, their weight, andyields (in mole percent) based on the starting quantity of benzylchloride entering their composition.

Percent Monobenzyl toluene, 264.7 grams 19.4

Dibenzyl toluene, 285 grams 28.0

Triand tetrabenzyl toluene, 285 grams 34.2 Undistilled residue, assumedpentatoluene, 91

grams 11.2

Total recovery 92.8

Example 2 To a stirred mixture of 1560 grams (17 moles) of dry tolueneand grams AlCl cooled with an ice-H01 bath, there were added 2365 grams(18.7 moles) benzyl chloride dropwise over a period of about one hourwith reaction temperature maintained at 0 to 12 C. The reaction mixturewas neutralized with 300 ml. dilute hydrochloric acid, the organic layerseparated out and extracted again with dilute HCl; aqueous layerdiscarded, and organic layer shaken thoroughly with 40% potassiumhydroxide solution. Organic layer removed from basic solution, driedover anhydrous K CO plus Celkate, filtered and distilled gave thefractions described below:

Fractions 3 and 4 and the pot residue provided useful materials, thelower fractions having too low a viscosity.

Example 3 A reaction was carried out between 830 grams (9 moles)toluene, 2530 grams (20 moles) benzyl chloride and 15 grams aluminumchloride at 6 to 18 C. over a two-hour period. Following acidneutralization, KOH extraction,

4 drying and decolorizing with K CO and Celkate and filtration, thereaction product was distilled with the following results:

Boiling Range, Refractive Viscosity, Weight,

Fraction C. (nun. Hg) Inder, cs. 25 C. Grains -245 (10) 1.5733 565242-282 (10) 1.6014 479 3... 186-306 (0.03) 1 6200 4, 896 831 Potresidue 581 Fraction 3 and the pot residue provided useful materials,Fractions 1 and 2 having too low a viscosity. The pot residue of thisexample was subjected to electron irradiation with a 1500 kv. resonanttransformer at a current input of 200-500 microarn-peres at a dose of20-50 10 rcentgens/rninute to a total dose of 2000 megaroentgens. Thetotal number of molecules of gas per 100 electron volts absorbed was0.079. The viscosity in centistokes prior to irradiation measured at 100C. was 255 and after irradiation the viscosity at 100 C. was 670. Thevery low gas value and the small change in viscosity under the aboveaccelerated test conditions show conclusively the eminent suitability ofthese compositions as a deformable medium in a projection system of thepresent type. When such compositions are placed in the projectionsystem, clear images are obtained and the fluid can be used over longperiods of time without [any apparent evidence of either degradation orgelation of the deformable medium.

Example 4 A reaction carried out as in Example 2 between 414 grams (4.5moles) toluene, 1253 grams (10 moles) benzyl chloride and 8 grams AlClproceeded at 11 to 18 C. over 1.4 hours. The usual washing and adsorbentprocedure afforded a filtrate which on distillation gave the followingcuts:

Boiling Range, Refractive Viscosity, Weight, Fraction 0. (mm. Hg)Ingitg, es. 25 C. Grams Example 5 I Boiling Range, Refractive Viscosity,Weight,

Fraction 0. (mm. Hg) Indg, 25 cs. Grains 1 122-134 (10) 1.5750 105 2146-277 (10) 1.6017 15 78 3 -316 (0.01) 1 6226 301 87 Pot residue 316(0. 01) 34 Fraction 3 with a volume resistivity of 6.9 10 ohmcm. as wellas the pot residue provided good media for the present purpose.

Example 6 6 product treated with anhydrous K CO and Celkate. Filtrationand then distillation afforded the following cuts:

40% KOH solution, the basic layer discarded and the lgoiling Range,Rei'ractiv e Viscosity Weight, There were reacted 117 grams (1.5 mole)benzene, 5 Fmemn (mm'Hg) 25 '8 Grams 380 grams (3 moles) benzyl chlorideand 4 grams AlCl carried out as in Example 5 over 2.1 hours and at 15 to1 114-175 1.5703 1,577 28 C. gave after the usual workup the followingcuts on g igfifi qgg "gig distillation. fot'residii'eiiiii 345 01151:388 10 Boiling Range, Refractive Viscosity, Weight, Fraction 3 and thepot residue were good media. This Fraction (mm'Hg) g' Grams exampleshows also that yields of polybenzylated aromatics can be significantlyincreased by successive benzyl- 122442 (10) M738 54 ations of lowmolecular weight by-products. Thus, h 2 160-266 10 1. 6013 53 aboveFraction 3 Was further stripped into a usable valve is g' a' i'gg E8182;5% fluid of 1738 cs. (25 C.) and of very good color.

Example 10 Fraction 3 W1th a volume reslstmiy of 1'8X1015.Ohm' Toeliminate possible oxidation and other undesirable as Well as the potresldue provlded good medla' side reactions in the polybenzyltoluenesynthesis, the Example 7 usual reaction was carried out under a drynitrogen blanket As in Example 78 grams (1 mole) benzene, 380 and thisis illlustraged 1indtle followking exafiilpllfi. Th ejbre;1 grams (3moles) benzyl chloride and 4 grams AlCl actlon Yeslse g us one l g H(anhydrous) were reacted. Normal workup of the re- Succssslve y pyrogaConcen me 2 action mixture gave on distillation the following pmolecular sieve and a d1benzyltoluene bubbler. With a ucts, slow streamof N flowing through, the vessel was charged with 3015 grams (33 moles)dry toluene and 40 to Boning Ra g R f V W ht grams A101 (anhydrous) andthe mixture cooled to 0 C. s n I e m Y. m 1 Added over a period of 1.5hours were 6260 grams (49.5 Fractlon Hg) 9 Grams 30 moles) of freshlydistilled benzyl chloride with reaction maintained at --7 to 0 C.Following the usual neutrali- 9 zation with dilute HCl acid (twice),extraction with hot 3 193 314(0 (05) 'g g 40% KOH solut1on, treatmentW1th anhydrous K CQ Potresidue 314 (0.05) 150 and Celkate andfiltration, the organic product was dis- 0 tilled giving, after removalof excess toluene, the cuts cited Fraction 3 with a volume resistivityof 2.0 10 below' ohm-cm. and the pot residue proved to be useful writingBoning Range Refractive Viscosity, Weight medla- Fraction 0. (mm. Hg)Index, 25" cs. 25 Grams Example 8 40 C. C.

This illustrates the preparation of polybenzyl-o-xylene.

1; mixture of 318 grams (3 moles) dry o-xylene and 4 to 3 iigl g igtgiilgi igg 1:155 fig grams AlCl (anhydrous) were cooled to 0 C. To i i thestirred pot were added 494 grams (3.911101 benzyl r Pmesldue 331 (0'04)958 chloride over 0.7 hour at 2 to +2 C. Evolution of HCl gas stoppedquickly and the dark red rea tio i Fraction 3 and the pot residue wereuseful media. After ture was neutralized by stirring in 150 ml. diluteHCl acid. the usual Stripping and Processing 3 fluid of 1792 The aqueouslayer was discarded and the organic product was Obtained With a Y P bluefluorescence and 0116 again washed with dilute HCl, followed by twoextrac- 0f the lightest yellow Colors yet mauledtions with hot 40% KOHsolution. Organic layer was 50 Example 11 then stirred with anhydrous KCO and Celkate and filtered. Distillation productd the followingfractions: Thls agam Illustrates the Preparatlon of polybenzyl toluene.A reactor was charged with 12,060 grams (132 moles) dry toluene and 100grams AlCl and the mixture Fraction hlifififi ilffilfii, gigi $5 55stirred and cooled. On reaching a temperature of 3 C.,

the addition of 25,040 grams (198 moles) of benzyl chloride was startedand carried out over three hours up to a 3 3:; g; final temperature of10 C. The reaction was stirred an 138 2? 1 1 g8 adgitiltlmal 01.75 hour,neutralized with dilute HCl acid 5 j 1 an t e pro uct stirred twice withtwo and four liter por- 212 350 (0 0001) 176212 3'5X107 25 tions of hot30% KOH solution and treated with 1200 grams anhydrous K2003 and 400grams Celkate. After Example 9 filtration a second treatment with 700grams Celkate was performed. Filtration gave a straw colored fluid fromThe synthesis of polybenzyltoluene from the reaction which excesstoluene was stripped. Distillation then gave of benzyl chloride withbenzyl toluene is demonstrated the following cuts: herein. Benzyltoluene (5460 grams, 30 moles) recovered from previous benzylations .andanhydrous AlCl (45 grams) were mixed and cooled to 3 C. To the Fractionl gfif g gy gfggi g fg gi resulting red-orange solution were added 3800grams 25 C. (30 moles) dry benzyl chloride over two hours and at 3 to +5C. Following neutralization of the mixture s5214 (10) 1.5693 3.4 6,307with one liter of dilute HCl acid and a subsequent dilute g?, 5%8} iffi553 3233 HCl acid wash, the organic layer was stirred with hot 950Fraction 3 and the pot residue were useful media.

A center cut of Fraction 3 was taken and after suitable stripping andprocessing had a viscosity of 1888 cs. at 25 C. and n =1.6l83.

There are provided, then, by the present invention media which becauseof their desirable viscosity, resistance to decomposition under electronbombardment, good resistivity, loW vapor pressure and compatibility ornonreactivity with other elements of the projection system are admirablysuited for the use described. It Will be realized that obviousmodifications of the invention may be made Without departing from thespirit or scope thereof.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a projection system comprising a container having conductinginterior, a deformable medium in said container, electron beam means forproducing an electrical charge on the surface of said deformable mediumas a function of an applied electrical signal and cooperating with saidconducting interior to subject the medium to a deforming force toproduce deformations in the surface of said medium and a light andoptical system for projecting light as a function of the deformations inthe surface of said medium, the improvement which comprises using assaid deformable medium the Friedel-Crafts reaction product of benzylchloride and a material selected from the class consisting of benzene,toluene, Xylene, benzyl toluene, diphenyl methane, and mixtures thereof,said product having a viscosity of at least 100 centistokes (cs.) at 25C.

2. In a projection system comprising a container having conductinginterior, a deformable medium in said container, electron beam means forproducing an electrical charge on the surface of said deformable mediumas a function of an applied electrical signal and cooperating with saidconducting interior to subject the medium to a deforming force toproduce deformations in the surface of said medium and a light andoptical system for projecting light as a function of the deformations inthe surface of said medium, the improvement which comprises using assaid deformable medium the Friedel-Crafts reaction product of benzylchloride and benzene, said product having a viscosity of at least 100centistokes (cs.) at 25 C.

3. In a projection system comprising a container having conductinginterior, a deformable medium in said container, electron beam means forproducing an electrical charge on the surface of said deformable mediumas a function of an applied electrical signal and cooperating with saidconducting interior to subject the medium to a deforming force toproduce deformations in the surface of said medium and a light andoptical system for projecting light as a function of the deformations inthe surface of said medium, the improvement which comprises using assaid deformable medium the Friedel-Crafts reaction product of benzylchloride and toluene, said product having a viscosity of at least 100centistokes (cs.) at 25 C.

4. In a projection system comprising a container having conductinginterior, a deformable medium in said container, electron beam means forproducing an electrical charge on the surface of said deformable mediumas a function of an applied electrical signal and cooperating with saidconducting interior to subject the medium to a deforming force toproduce deformations in the surface of said medium and a light andoptical system for projecting light as a function of the deformations inthe surface of said medium, the improvement which comprises using assaid deformable medium the Friedel-Crafts reaction product of benzylchloride and Xylene, said product having a viscosity of at leastcentistokes (cs.) at 25 C.

5. In a projection system comprising a container having conductinginterior, a deformable medium in said container, electron beam means forproducing an electrical charge on the surface of said deformable mediumas a function of an applied electrical signal and cooperating with saidconducting interior to subject the medium to a deforming force toproduce deformations in the surface of said medium and a light andoptical system for projecting light as a function of the deformations inthe surface of said medium, the improvement which comprises using assaid deformable medium the Friedel-Crafts reaction product of benzylchloride and benzyl toluene, said product having a viscosity of at least100 centistokes (cs.) at 25 C.

6. In a projection system comprising a container having conductinginterior, a deformable medium in said container, electron beam means forproducing an electrical charge on the surface of said deformable mediumas a function of an applied electrical signal and cooperating with saidconducting interior to subject the medium to a deforming force toproduce deformations in the surface of said medium and a light andoptical system for projecting light as a function of the deformations inthe surface of said medium, the improvement which comprises using assaid deformable medium the Friedel-Crafts reaction product of benzylchloride and diphenyl methane, said product having a visocsity of atleast 100 centistokes (cs.) at 25 C.

References Cited by the Examiner UNITED STATES PATENTS 2,943,147 6/1960Glenn 1787.5 3,006,972 10/1961 Fields et a1. 260668 3,109,868 11/1963Fields et a1. 260668 OTHER REFERENCES Radziewanonski, Berichte: vol. 27,pp. 3235-3238 (p. 3237 particularly relied upon).

DAVID G. REDINBAUGH, Primary Examiner.

I. MCHUGH, Assistant Examiner.

1. IN A PROJECTION SYSTEM COMPRISING A CONTAINER HAVING CONDUCINGINTERIOR, A DEFORMABLE MEDIUM IN SAID CONTAINER, ELECTRON BEAM MEANS FORPRODUCING AN ELECTRICAL CHARGE ON THE SURFACE OF SAID DEFORMABLE MEDIUMAS A FUNCTION OF AN APPLIED ELECTRICAL SIGNAL AND COOPERATING WITH SAIDCONDUCTING INTERIOR TO SUBJECT THE MEDIUM TO A DEFORMING FORCE TOPRODUCE DEFORMATIONS IN THE SURFACE OF